Methods of image formation by electrophotography include a method comprising forming a toner image on an electrophotographic photoreceptor, such as a selenium drum, and transferring the toner image to paper, a method comprising forming a toner image on a recording material comprising a support, e.g., paper, film, etc., having provided thereon a photoconductive layer, and the like.
Through extension of application of these image formation methods, an electrophotographic photoreceptor comprising a light-transmitting conductive support having provided thereon a transparent organic photoconductive layer has recently been developed as a recording material in the field of microfilms and the like (see Optical Eng., Vol. 20, No. 3, 365 (1981), and Japanese Patent Application (OPI) No. 238841/86 (the term "OPI" as used herein means "unexamined published application")). According to this system, a toner image is electrophotographically formed on the light-transmitting photoreceptor, and the image recorded can be seen whenever necessary by means of transmitted light by enlarging projection or making copies.
On the other hand, an electrophotographic system using a laser as a light source has been developed recently. Lasers used include gas lasers, e.g., an He-Ne laser, etc., and semiconductor lasers, e.g., a Ga-Al-As laser, etc. The semiconductor lasers have great advantages over the gas lasers, such as a small size, low cost, capability of direct modulation, and the like.
However, such a laser, when applied as a light source for recording on the aforesaid light-transmitting electrophotographic photoreceptor, causes potential unevenness like interference fringes on the surface of the receptor, which results in non-uniform density upon toner development of the electrostatic latent image. In order to prevent generation of similar interference fringes on electrophotographic photoreceptors using an opaque support for a laser beam printer, it has been proposed to use a conductive support having a roughened surface as disclosed in Japanese Patent Application (OPI) Nos. 162975/83, 171057/83 and 112049/85; to provide a subbing layer having a rough surface with no gloss between a conductive support and a photosensitive layer as disclosed in Japanese Patent Application (OPI) No. 172047/85; or to provide a subbing layer having dispersed therein titanium black between a conductive support and a photosensitive layer as disclosed in Japanese Patent Application (OPI) No. 184258/85. However, provision of such a subbing layer between a conductive layer and a conductive support of the above-described light-transmitting photoreceptor does not produce fully satisfactory effects. In particular, the presence of a titanium black-dispersed layer rather causes a hinderance to reading of the recorded image by transmitted light.